This study is designed to test both short and long term effects of behavioral intervention on the growth and development of infants with Intrauterine Growth Retardation. The effects of the intervention will be assessed on a group of 150 preterm infants (GA <37 weeks) up to 18 months of age and a second cohort of 105 full-term infants at 3 and 4 years of age. The effects of the intervention will be assessed on mother-infant interaction, caloric intake, growth velocities of weight, length, head circumference, ponderal Index, and skinfold thickness, and developmental outcome (cognitive, linguistic and behavioral status). It is expected that symmetric IUGR preterm infants without intervention will have the lowest feeding interaction scores, the slowest physical growth and poorer developmental outcome. Full-term IUGR infants, without intervention, will have the slowest physical growth and those coming from low SES families, the poorest developmental outcome.